It is estimated that each year, between 300,000 and 600,000 people in the United States are negatively affected by deep vein thrombosis (DVT) and pulmonary embolism (PE). Further, it is estimated that between 60,000 and 100,000 people in the United States die each year as a result of venous thromboembolism (VTE), a disease that includes both DVT and PE, and occurs when a blood clot breaks loose and travels in the blood towards the lungs. Patients who are at risk of developing DVT or PE but cannot undergo anticoagulation therapy due to bleeding complications or ineffectiveness may opt for a vascular filter implant as an alternative treatment. Patients undergoing surgery for blunt trauma, penetrating trauma, and falls also benefit from vascular filters. These filters, commonly called inferior vena cava (IVC) filters, capture dislodged blood clots from the inferior vena cava and iliac veins before they can reach the lungs and heart.
A typical IVC filter consists of several wire legs arranged in a small conical shape. The filter is inserted into the IVC through either the jugular vein in the neck or the femoral vein in the groin, with the mouth of the cone facing towards the oncoming flow of blood. Barbs on the filter legs secure the filter to the internal walls of the vein, and the conical shape of the legs permits normal blood flow while capturing and holding loose blood clots and emboli.
After insertion, these filters may only be retrieved from one direction (the jugular or the femoral vein). Migration within the patient may cause the filter to tilt, positioning the retrieval hook in apposition to the blood vessel wall and out of reach of the filter retrieval device. The filter legs may also adhere to and even perforate the vessel wall, which may require an invasive surgical removal of the filter, increasing treatment costs and risk of complications to the patient. Further, a tilted filter changes the cross-sectional profile of the filter relative to the oncoming flow path of blood, which can lead to an inefficient and sub-optimal filter performance. Still further, some filters, such as the OPTEASE® IVC filter (Cordis Corp., Freemont, Calif., USA) have features at either pole that potentially push the incoming clot towards vessel walls and thereby increase the incidence of in-situ thrombus formation and filter occlusion. A recent attempt to create an improved retrievable IVC filter is the Crux® vena cava filter (Volcano Corp., San Diego, Calif., USA), which can be deployed and retrieved from either the jugular or femoral veins. However, the design of these types of filters leads to significant contact along the vessel wall and therefore does not minimize the problem of adhesions. Also, such elongated filters cannot be placed in patients with a short infrarenal IVC. Further, recent studies have also shown an increased incidence of DVT in patients with conventional filters, which may be linked to thrombotic occlusion of the filter leading to venous stasis upstream in the legs.
Thus, there is need in the art for a removable IVC filter that is less likely to adhere to a vessel wall, can be bidirectionally deployed and retrieved, minimizes the occurrence of tilt after deployment, minimizes the risk of vessel perforation, may be adjustable during deployment, and minimizes the occurrence of thrombotic occlusion in the filter. The present invention satisfies these needs.